In various applications, an irregular arrangement of sensors is used or available for sensing information and providing indicia of this information. The irregularity of the arrangement can significantly decrease the accuracy of the representation of a particular stimulus. This is especially true when using a regularly-disposed arrangement of exciters to excite the irregularly-arranged sensors.
For example, functional retinal ganglion cell sensors are irregularly arranged in persons, especially those with retinal degradation who have lost most or all of their photoreceptor cells. Such loss may occur as a result of age-related macular degeneration or retinitis pigmentosa, which together cause blindness in millions of people worldwide. In such cases, even though photoreceptor cells are lost, about 30% of retinal ganglion cells survive, and these cells are still capable of relaying signals to the brain. The surviving ganglion cells actively migrate and form anomalously re-wired circuits. This re-wiring causes unavoidable irregularities at the retina-brain interface because it is not known a priori how electrical pulses on a given portion of the retina will be perceived by the brain.
Retinal prosthetic devices hold great promise in restoring partial vision to blind patients who have lost their photoreceptor cells. Retinal implants utilize a video camera as a replacement for photoreceptors transducing light patterns, and an array of electrodes positioned on the retina to deliver electrical signals based on the camera output to the retinal ganglion cells. Due to the ganglion cell irregularity, light sensed by the camera at a particular location in a field of view that is translated into a corresponding signal for an electrode at a similar relative position in the retinal implant may not be perceived by the person as light emanating from the particular location in the field of view, but from a different location.